#include "../head/md5.h"
#include "../head/basic_head.h"

#define READ_DATA_SIZE 1024
#define MD5_SIZE 16
#define MD5_STR_LEN (MD5_SIZE * 2)

unsigned char PADDING[] =
	{
		0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

void MD5Init(MD5_CTX *context)
{
	context->count[0] = 0;
	context->count[1] = 0;
	context->state[0] = 0x67452301;
	context->state[1] = 0xEFCDAB89;
	context->state[2] = 0x98BADCFE;
	context->state[3] = 0x10325476;
}

void MD5Update(MD5_CTX *context, unsigned char *input, unsigned int inputlen)
{
	unsigned int i = 0;
	unsigned int index = 0;
	unsigned int partlen = 0;

	index = (context->count[0] >> 3) & 0x3F;
	partlen = 64 - index;
	context->count[0] += inputlen << 3;

	if (context->count[0] < (inputlen << 3))
		context->count[1]++;
	context->count[1] += inputlen >> 29;

	if (inputlen >= partlen)
	{
		memcpy(&context->buffer[index], input, partlen);
		MD5Transform(context->state, context->buffer);

		for (i = partlen; i + 64 <= inputlen; i += 64)
			MD5Transform(context->state, &input[i]);

		index = 0;
	}
	else
	{
		i = 0;
	}
	memcpy(&context->buffer[index], &input[i], inputlen - i);
}

void MD5Final(MD5_CTX *context, unsigned char digest[16])
{
	unsigned int index = 0, padlen = 0;
	unsigned char bits[8];

	index = (context->count[0] >> 3) & 0x3F;
	padlen = (index < 56) ? (56 - index) : (120 - index);
	MD5Encode(bits, context->count, 8);
	MD5Update(context, PADDING, padlen);
	MD5Update(context, bits, 8);
	MD5Encode(digest, context->state, 16);
}

void MD5Encode(unsigned char *output, unsigned int *input, unsigned int len)
{
	unsigned int i = 0;
	unsigned int j = 0;

	while (j < len)
	{
		output[j] = input[i] & 0xFF;
		output[j + 1] = (input[i] >> 8) & 0xFF;
		output[j + 2] = (input[i] >> 16) & 0xFF;
		output[j + 3] = (input[i] >> 24) & 0xFF;
		i++;
		j += 4;
	}
}

void MD5Decode(unsigned int *output, unsigned char *input, unsigned int len)
{
	unsigned int i = 0;
	unsigned int j = 0;

	while (j < len)
	{
		output[i] = (input[j]) |
					(input[j + 1] << 8) |
					(input[j + 2] << 16) |
					(input[j + 3] << 24);
		i++;
		j += 4;
	}
}

void MD5Transform(unsigned int state[4], unsigned char block[64])
{
	unsigned int a = state[0];
	unsigned int b = state[1];
	unsigned int c = state[2];
	unsigned int d = state[3];
	unsigned int x[64];

	MD5Decode(x, block, 64);

	FF(a, b, c, d, x[0], 7, 0xd76aa478);   /* 1 */
	FF(d, a, b, c, x[1], 12, 0xe8c7b756);  /* 2 */
	FF(c, d, a, b, x[2], 17, 0x242070db);  /* 3 */
	FF(b, c, d, a, x[3], 22, 0xc1bdceee);  /* 4 */
	FF(a, b, c, d, x[4], 7, 0xf57c0faf);   /* 5 */
	FF(d, a, b, c, x[5], 12, 0x4787c62a);  /* 6 */
	FF(c, d, a, b, x[6], 17, 0xa8304613);  /* 7 */
	FF(b, c, d, a, x[7], 22, 0xfd469501);  /* 8 */
	FF(a, b, c, d, x[8], 7, 0x698098d8);   /* 9 */
	FF(d, a, b, c, x[9], 12, 0x8b44f7af);  /* 10 */
	FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
	FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
	FF(a, b, c, d, x[12], 7, 0x6b901122);  /* 13 */
	FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
	FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
	FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

	/* Round 2 */
	GG(a, b, c, d, x[1], 5, 0xf61e2562);   /* 17 */
	GG(d, a, b, c, x[6], 9, 0xc040b340);   /* 18 */
	GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
	GG(b, c, d, a, x[0], 20, 0xe9b6c7aa);  /* 20 */
	GG(a, b, c, d, x[5], 5, 0xd62f105d);   /* 21 */
	GG(d, a, b, c, x[10], 9, 0x2441453);   /* 22 */
	GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
	GG(b, c, d, a, x[4], 20, 0xe7d3fbc8);  /* 24 */
	GG(a, b, c, d, x[9], 5, 0x21e1cde6);   /* 25 */
	GG(d, a, b, c, x[14], 9, 0xc33707d6);  /* 26 */
	GG(c, d, a, b, x[3], 14, 0xf4d50d87);  /* 27 */
	GG(b, c, d, a, x[8], 20, 0x455a14ed);  /* 28 */
	GG(a, b, c, d, x[13], 5, 0xa9e3e905);  /* 29 */
	GG(d, a, b, c, x[2], 9, 0xfcefa3f8);   /* 30 */
	GG(c, d, a, b, x[7], 14, 0x676f02d9);  /* 31 */
	GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

	/* Round 3 */
	HH(a, b, c, d, x[5], 4, 0xfffa3942);   /* 33 */
	HH(d, a, b, c, x[8], 11, 0x8771f681);  /* 34 */
	HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
	HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
	HH(a, b, c, d, x[1], 4, 0xa4beea44);   /* 37 */
	HH(d, a, b, c, x[4], 11, 0x4bdecfa9);  /* 38 */
	HH(c, d, a, b, x[7], 16, 0xf6bb4b60);  /* 39 */
	HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
	HH(a, b, c, d, x[13], 4, 0x289b7ec6);  /* 41 */
	HH(d, a, b, c, x[0], 11, 0xeaa127fa);  /* 42 */
	HH(c, d, a, b, x[3], 16, 0xd4ef3085);  /* 43 */
	HH(b, c, d, a, x[6], 23, 0x4881d05);   /* 44 */
	HH(a, b, c, d, x[9], 4, 0xd9d4d039);   /* 45 */
	HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
	HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
	HH(b, c, d, a, x[2], 23, 0xc4ac5665);  /* 48 */

	/* Round 4 */
	II(a, b, c, d, x[0], 6, 0xf4292244);   /* 49 */
	II(d, a, b, c, x[7], 10, 0x432aff97);  /* 50 */
	II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
	II(b, c, d, a, x[5], 21, 0xfc93a039);  /* 52 */
	II(a, b, c, d, x[12], 6, 0x655b59c3);  /* 53 */
	II(d, a, b, c, x[3], 10, 0x8f0ccc92);  /* 54 */
	II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
	II(b, c, d, a, x[1], 21, 0x85845dd1);  /* 56 */
	II(a, b, c, d, x[8], 6, 0x6fa87e4f);   /* 57 */
	II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
	II(c, d, a, b, x[6], 15, 0xa3014314);  /* 59 */
	II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
	II(a, b, c, d, x[4], 6, 0xf7537e82);   /* 61 */
	II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
	II(c, d, a, b, x[2], 15, 0x2ad7d2bb);  /* 63 */
	II(b, c, d, a, x[9], 21, 0xeb86d391);  /* 64 */
	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
}

int compute_file_md5(int fd, char *md5_str)
{
	int i;
	int ret;
	unsigned char data[READ_DATA_SIZE];
	unsigned char md5_value[MD5_SIZE];
	MD5_CTX md5;

	// init md5
	MD5Init(&md5);

	while (1)
	{
		ret = read(fd, data, READ_DATA_SIZE);
		if (-1 == ret)
		{
			perror("read");
			return -1;
		}

		MD5Update(&md5, data, ret);

		if (0 == ret || ret < READ_DATA_SIZE)
		{
			break;
		}
	}

	MD5Final(&md5, md5_value);

	for (i = 0; i < MD5_SIZE; i++)
	{
		snprintf(md5_str + i * 2, 2 + 1, "%02x", md5_value[i]);
	}
	md5_str[MD5_STR_LEN] = '\0'; // add end

	return 0;
}
